<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	<style type="text/css">
		#box{
			width: 100px;
			height: 100px;
			background: purple;
			transition: all 1s;
		}
		#box:hover{
			width: 500px;
		}
	</style>
	</head>
	<body>
		
	<div id="box"></div>
		
		
	</body>
</html>
